The disclosure relates to an encapsulation, a microelectromechanical system (MEMS), and a method for encapsulating a sensitive component structure on a semiconductor substrate.
Sensitive, mainly mechanical, component structures of MEMS have to be encapsulated for protection against damage. Inertial sensors, such as acceleration sensors or rate-of-rotation sensors, are currently covered with KOH-etched silicon caps, the caps being connected with the aid of a seal glass connection on the semiconductor substrate having the sensitive component structure. A further established method for encapsulating sensitive component structures on semiconductor substrates is the anodic bonding of three-dimensionally structured glass wafers. In addition, structured silicon wafers as encapsulation are fixed to semiconductor substrates by various bonding methods. What is common to all the aforementioned methods is that a cost-intensive, three-dimensionally structured cap composed of silicon or glass is used.
DE 100 06 446 A1 describes a method for encapsulating sensitive component structures in the wafer stage. The known encapsulation comprises a frame structure composed of a cured reaction resin, said frame structure enclosing the component structure, and also a planar cap consisting of a flat (two-dimensional) plastic film and a cured reaction resin layer arranged thereabove, said cap covering the frame structure and forming a hollow space with the latter. What is disadvantageous about the known encapsulation is the complex production method thereof using an auxiliary film that firstly has to be applied and then has to be removed again.
US 2002/0121701 A1 describes an encapsulation method for encapsulating a non-MEMS wafer, wherein, in order to encapsulate the semiconductor substrate, the latter is coated with an initially liquid polymer layer. The known encapsulation is not suitable for MEMS owing to a lack of cavities.